textproduct: Albany

WHAT HAS CHANGED

Patchy fog was expanded further across eastern NY and western New England tonight in the moist air mass before the cold advection increases in the wake of the occluded front late tonight.

Patchy radiational mist/fog was included across the sheltered valleys Tue night/Wed morning.

Friday into the weekend looks potentially unsettled with a wave moving along the boundary stalled south of the region initially, as well as a deepening mid and upper level trough over the Great Lakes Region into the Northeast with a closed low that may bring periods of rain especially late in the weekend.

KEY MESSAGES

1)Scattered showers and isolated to scattered non-severe thunderstorms will move across the region this afternoon through tonight ahead of the occluded front.

2) Another round of isolated to scattered showers, with isolated thunderstorms, is expected Wed pm into Thu, as a cold front slowly moves across the region.

3) Potentially, unsettled weather returns Fri into the weekend as a broad mid and upper level trough settles in, although there is low confidence in the timing, rainfall amounts and details with this system.

DISCUSSION

KEY MESSAGE 1... A cold front associated with low pressure over southeast Quebec is catching up to a warm front over central NY and PA early this afternoon, as a secondary low moves across southeast New England. A moist and humid air mass will briefly impact the region with dewpoints in the 60s to lower 70s this afternoon. An occluded front will bring some scattered showers and isolated to scattered thunderstorms. PWATS have risen into the 1.5-2.0" range across the forecast area based on the SPC RAP Mesoanalysis, as the 12Z KALY sounding was 1.94". Low-level stratus is slowly eroding to partly to mostly cloudy conditions this afternoon. SBCAPE has had trouble developing from the Hudson River Valley/I-87 eastward so far. SBCAPEs 500-1000 J/kg have been materializing north and west over the southwest Adirondacks. The latest HREFs has mean SBCAPES of 750-1250 J/kg late this afternoon into this evening from southern VT, the Capital Region, and the eastern Catskills south and east with weak deep shear 15-25 KT. The best 0-6 km bulk shear 25-35 KT is over the far northwest zones, where some showers and isolated thunderstorms are developing over the western Adirondacks. The lack of robust instability, deep shear over the majority the forecast area, and weak lapse rates aloft should keep the thunderstorms that form non-severe. Some gusty winds and brief localized downpours could produce ponding of water with a few storms.

The front will move across the region slowly tonight with the abundant low-level moisture remaining in place, as widespread patchy fog to localized areas of dense fog will likely form, especially where rain occurs. Lows fall back into the mid 50s to mid 60s with the coolest readings west of the Hudson River Valley over the higher terrain. Some modest cold advection will occur over the northwest zones late.

KEY MESSAGE 2...

A few lingering showers persist over southern VT in the morning, as high pressure builds in across the region with partly to mostly sunny conditions and seasonable temps. High will be seasonable in the the 80-85F range in the valleys and mainly 70s over the hills and mtns. A window of mostly clear skies and light to calm winds will allow for some patchy radiational valley mist/fog in the sheltered valleys, as lows will be in the 50s around 60F. The frontal boundary approaches for Wed with a slight to low chance of showers and thunderstorms especially north and west of the Capital Region over the western Dacks and west-central Mohawk Valley. Instability looks weak or limited with west-southwest low to mid-level flow. The front looks to weaken at night with the showers/thunderstorms diminishing. Temps will run near or slightly above seasonal normals with 70s to lower/mid 80s. The frontal boundary makes slow progress across the region by Thu morning. The best chance for isolated to scattered thunderstorms will be along and southeast of southern VT, the Greater Capital Region, and the eastern Catskills in the afternoon. A few thunderstorms could become strong, if moderate instability increases, but that is unclear at this this time with the medium range guidance/ensembles.

KEY MESSAGE 3...

Some uncertainty continues Fri into the weekend. Some of the medium range guidance has a wave developing along the stalled front to the south of the region over PA and NJ for some rain to impact locations from the Capital Region south and east, while the ECMWF and some ensembles keep it dry with high pressure building in. Our latest forecast from WPC for Days 4-7 keeps it dry outside a slight chance of showers closer to I-84 on Fri. The deterministic, AI and ensemble guidance continues to forecast a broad, deepening mid and upper level trough over southeast Canada, the Great Lakes Region and the Northeast for the upcoming weekend into early next week. The chances of showers and few thunderstorms continue late Sat into Sun for the trough and a potential closed low. Some locally heavy rain could occur depending where the mid and upper level low track and any surface cyclones, but timing, evolution details and the amount of rainfall still look very uncertain at this time. We will continue to closely monitor trends through the week, as this storm system is still several days away. Temps trend slightly cooler than normal.

AVIATION /18Z MONDAY THROUGH SATURDAY/

We start the TAF period with either low VFR or MVFR conditions at all TAF sites. Through 18/00z, MVFR and low VFR ceilings continue to fluctuate due to passing rain showers and low stratus clouds. Between 17/20z and 18/00z, all TAF sites could see a passing rain shower. Forecast confidence is low for a thunderstorm this afternoon, with a vicinity thunderstorm the most likely scenario for this timeframe. So with higher confidence for rain shower activity, continued mentioned rain showers in PROB30 groups through 18/00z. Then, low stratus and patchy fog develop for the overnight hours as winds become calm and conditions are favorable, especially any TAF site that sees a rain shower today. Confidence is highest for KPSF to develop fog which has been introduced for 18/06z through 18/13z with LIFR/IFR conditions. KGFL could see some patchy fog for MVFR conditions between 3z and 6z, but low ceilings due to low stratus will likely persist after 6z through 12z. For KALB and KPOU, IFR ceilings are likely in store after 6z through 10-12z due to low ceilings.

Outlook...

Tuesday Night: No Operational Impact. Patchy FG. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Low Operational Impact. Slight Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.